package ink.yuanchu.picachoframework.security;

import ink.yuanchu.picachoframework.util.JwtTokenUtil;
import org.apache.commons.lang3.StringUtils;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.authentication.www.BasicAuthenticationFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
/**
 * Created with IntelliJ IDEA.
 *
 * @author ziyuan
 * @Date: 2021/02/20/12:47
 * @Description:
 */
public class JWTAuthorizationFilter extends BasicAuthenticationFilter {

        public JWTAuthorizationFilter(AuthenticationManager authenticationManager) {
            super(authenticationManager);
        }

        /**
         * 在过滤之前和之后执行的事件
         */
        @Override
        protected void doFilterInternal(HttpServletRequest request,HttpServletResponse response,FilterChain chain) throws IOException, ServletException {
            String tokenHeader = request.getHeader(JwtTokenUtil.TOKEN_HEADER);

            // 若请求头中没有Authorization信息 或是Authorization不以Bearer开头 则直接放行
            if (tokenHeader == null || !tokenHeader.startsWith(JwtTokenUtil.TOKEN_PREFIX)){
                chain.doFilter(request, response);
                return;
            }

            // 若请求头中有token 则调用下面的方法进行解析 并设置认证信息
            SecurityContextHolder.getContext().setAuthentication(getAuthentication(tokenHeader));
            super.doFilterInternal(request, response, chain);
        }

        /**
         * 从token中获取用户信息并新建一个token
         *
         * @param tokenHeader 字符串形式的Token请求头
         * @return 带用户名和密码以及权限的Authentication
         */
        private UsernamePasswordAuthenticationToken getAuthentication(String tokenHeader) {
            // 去掉前缀 获取Token字符串
            String token = tokenHeader.replace(JwtTokenUtil.TOKEN_PREFIX, "");
            // 从Token中解密获取用户名
            String username = JwtTokenUtil.getUsername(token);
            // 从Token中解密获取用户角色
            String role = JwtTokenUtil.getUserRole(token);
            // 将[ROLE_XXX,ROLE_YYY]格式的角色字符串转换为数组
            String[] roles = StringUtils.strip(role, "[]").split(", ");
            Collection<SimpleGrantedAuthority> authorities=new ArrayList<>();
            for (String s:roles) {
                authorities.add(new SimpleGrantedAuthority(s));
            }
            if (username != null) {
                return new UsernamePasswordAuthenticationToken(username, null,authorities);
            }
            return null;
        }
}

